Power actuator



Jpl'yfzo 1926.

y 1,592,919 c. s. BRAGG ET AL FOYER ACTUATOR Original Filed June 26, 1924 2 Sheefcs-Sheet 1 July 20,1926. l 1,592,919

C. S. BRAGG ET AL POWER ACTUATOR Original Filed June 26, 1924 2,Sheets-Shee t 2 mRNEY Patented July zo, 1926.

UNITED STATES `PATENT OFFICE.

CALEB S. BRAGG, OF PALM BEACH, FLORIDA, AND VICTOR W. KLIESRATH, OF PORT WASHINGTON, NEW YORK, ASSIGNORS TO BRAGG-KLIESRATH "CORPORATION, OI LONG ISLAND CITY, NEW YORK, A CORPORATION OF NEW YORK.

POWER ACTUATOR.

Original applicationV nled June 26, 1924, Serial No. 722,487. Divided and this application led January 31, 1925. Serial No. 5,948.

Our invention consists in the novel features hereinafter described, reference being.

- and the said invention is fully disclosed in `particularly with automobiles the following description and claims.

This application is a division of our former lapplication iile'd June 26, 1924, and given Serial No. 7 22,487.- l

In carryingout our invention we employ a power actuator especially adapted for use in brake mechanisms for automobiles and provided with brakes on all foul'. of the "supporting wheels, the actuator being provided' with two pistons working in'the same cylinder, each of which pistons is operatively connected with the brake mechanism for two wheels, preferably arranged opposite to each other at the same end of the chassis. The pistons are caused to move in the cylinder toward and from each other lby establishing `differential pressures between thatportion of the cylinder between the pistons and the portions at `each end of the cylinder on the opposite sides of the piston, and we provide reversing valve mechanism connected with an operator operated de vice for controlling the' movements of said pistons, the valve mechanism being constructed to maintain the pistons in balanced condition at any interjacent position of the valve mechanism between its limits of movement, so that the movements of the pistons and their connected brakemechanisms can be controlled with the utmost delicacy,

While the operator is relieved from the exertion of actually operating the brake mechanism. Thev valve mechanism is also connected to one of the pistons by means permitting lost motion, so. that in case of failure of the power, the said piston and its connected brake mechanism may nevertheless be operated directly by the operator.

In the application of our improved mechanism to autbmobiles in which an internal combustion engine furnishes the propelling power, the internal combustion engine affords a. convenient means of obtaining the differential pressures required. Thus, in

' the operation of an internal combustion engine, there is suction produced by the cylinders in drawing in the charges of explosive mixture, between the cylinders and the throttle valve which is at its maximum when the engine is throttled down, and decreases as the throttle is opened. There is also high compression in the cylinders of the engine which is greatest when the throttle is wide open, and decreases as the throttle is closed. Our improved power actuator, can, therefore, be readily operated by the suction from the intake manifold as the low pressure acting on one face of each piston, and atmospheric air as the high pressure acting on the opposite face of each piston, or by compressed gases from a cylinder of the engine providing the high pressure acting on'one face of-each piston and atmospheric air as the low pressure acting on the other face of each piston, or compressed gases from a cylinder of the engine may be employed as the high pressure and suction from the intake manifold may be employed as the low pressure. In practice, however, we find it most convenient and advantageous to employ the suction from the intake -manifold for the lowpressure and atmos- Ameans for preventing one of the pistons from movement in the cylinder and thereby holding out of operation the brake mechanism connected therewith, leaving the other piston to operate the brake mechanism connected to it so that in a four wheel brake mechanism for example, the operator operated part, as the foot lever, may be openated under normal conditions so as to apply only two of the brakes, as those for the rear Wheels, while in an emergency, or when heavybraking action is required, the locked piston may be released so that both pistons will operate, and simultaneously apply the brakes of all four of the wheels, when required, and under the entire control of the)l operator. In this instance this is accomplished by providing mechanical means for locking and unlocking the free piston notoperone for each of the wheels thereof, and having our improved double piston power actuator operatively connected therewith, and' with the intake manifold of the engine for supplying the lower pressure for operating the power actuator.

Fig. 2 is an enlarged sectional view of the double piston power actuator.

Fig. 2a is a detail drawn toian enlarged scale, showing the parts at the left o Fig. 2.

Fig. 2b is a section on the line 2b b of Fig. 2a looking in the direction of the arrow.

Figs. 3 and 4 are enlarged sectional views of a form of valve mechanism whiclrmay be conveniently employed in connection with the power actuator, showing the valve mechanism in reversed positions.

Referring to the drawings, 201, represents the power cylinder of our improved power actuator, both ends being closed by suitable heads, indicated at 202203 respectively, secured to the cylinder by any suitable means, as by connecting bolts and nuts, 204, see Fig. 1. Within the cylinder, 201, is a main double-acting piston, indicated at 210, provided with annular gaskets, 211, extending in opposite directions and engaging the inner surface of the cylinder wall. The piston, 210 is provided with a h ollow piston rod, 212, which extends through a guiding sleeve, 213, bushing, 214, and stuing box. 215, with which the, head, 203, of the cylinder is provided. The cylinder is also providedl with a second piston, 210, which we term the auxlhary or Heating piston, having similar gas'- kets, 211, extending in opposite directions, and engaging the inner surface of the cylinder. The piston 2103, is provided with a hollow piston rod, 212, extending through a guiding sleeve, 213, bushing, 214, and stuing box, 215", with which the head 202, of the cylinder is provided. The opposite ends o f the cylinder are connected by means of a plpe, er passage, 270, so that one or both of said pistons may be actuated bycreat.- lng differential pressures in the space, A1, between said pistons and the connected spaces, B, B3 at the opposite ends of the cylinder. 216, 216 represents a longitudinally movable valve sleeve extending in opposite di- `rections from the reversing valve mechanism, which in this instance is located in the hub of the main piston, 210. The piston, 210, is provided with two chambers, indicated respectively at 228 and 230. The chamber` 228, is connected by passages, 239-240 with the central portion, A1, of the cylinder between the pistons, while the chamber, 230, 1s connected by passage, 236, with the portron, B2, in the end of the cylinder beyond the piston, 210, which, through -the pipe or passage, 270, is connected to the portion, B3. Within the chamber, 228, is a valve collar, 227, secured to the valve'sleeve, which is ground to it the interior of the chamber,

extreme position, the said ports, 225, being maintained closed when in an interadjacent position between the limits of movement of the valve mechanism. Within the chambar, 230, the valve mechanism is provided with a collar valve, 229, ground to tit the wall of the chamber and movable within said chamber lbetween end washers, 229% and 229", and the portion, 216a of the valve sleeve is providedwith a plurality of suction ports, indicated at 224, which are capable of being brought into communication with the chamber, 230, in one extreme movement of the valve mechanism and into communication with the central space, A1, of the cylinder when in the other extreme position of the 'valve mechanism, said ports being normally closed when the valve mechanismis in an interadjacent position. For convenience of reference we term the ports, 224, the low pressure ports, and the ports, 225, the high pressure ports. y.

In this instance, as shown in Figs. 1 and 2, the low pressure is supplied by suction from the intake manifold, 221, of the internal combustion engine, 222, of the automobile which is connected to an inlet port, 220, in the exterior portion of the piston rod, 212, by a fiexible connection permitting the necessary movement of the piston rod.

In order to insure the instantaneous operation of the brake mechanism without interference with idling of motor, etc., we prefer to interpose a vacuum tank between the intake manifold and the actuator, and in Fig. 1, we have shown such a tank at 223% connected by a pipe 223, with the intake manifold. said pipe being preferably provided with a regulating valve, 223, adjacent to the manifold, and a check valve 223". adjacent to the tank. A flexible pipe, 223, which may be of considerable diameter. extends from the tank, 223, to the ports,- 220. Communication between the port. 220. and the low pressure ports. 224. is established through the hollow piston rod, 212, and the movable valve sleeve section, 216% i In order to further provide for cutting off ythe suction when the pistons are in retracted positions. which isthe normal or off position of the pistons. as indicated in Fig. 2. we prefer to provide the hollow piston rod .65 manner with the brake mechanisms for the/ i 212* with a plug or partition 218* permanently secured therein adjacent tothe .port 220, and provided with an axial aperture 218" and a valve seat 218 asbest shown in Fig. 2". We also provide a valve 218 for engaging the valve seat 218c when the parts are in normal of olf position, said valve I being secured to a rod 209, extending through the hollow piston rod, and being connected to the sleeve section 216', by means providing lost motion, in this instance a wrist pin 219, on the rod 209, engaging a slot 219 in the sleeve section. Vvlhen the pistons move away from each other and return to normal or retracted positions as shown in Fig. 2 the wrist pin 219 will be engaged by the end of slot 219, in the sleeve 216a and this will draw the valve 218 firmly upon its seat and form an additional sealing means when the parts are not in operation. lW'hen thevalve sleeve 2168L is moved in the direction of the arrow in Fig. 2, the end-of slot 219 Arelieves the wrist pin 219, and permits the valve 218 to open y suction, and it will be assisted in opening by the frictional engagement between valve sleeve, 216a, and the wrist pin. The valve 218 will remain open until it is closed by the return of the pistons and valve sleeve 216Il to normal or .retracted positions. The slot 219n permits the valve sleeve to move in the direction' of the arrow, Fig. 2, to a greater or less extent as required without interference from the valve rod 209. A

The higher pressure Huid in this instance is atmospheric air, which is admitted to thev interior of `the valve sleeve section, 2 16, through a port or opening, 243, at the outer end of the valve sleeve section, and preferably provided in a plug, 241, screwed into the outer end of the hollow piston rod, 212, and provided with perforated ears, 242, by

which itis connected to one pair of brake mechanisms, as the brakes for the rear wheels of the automobile. The outer end of the other piston rod, 212, is provided with similar ears, 242, by which it is connected to the remaining brake mechanisms, as the brakes for the front wheels. In the present instance as shown in Fig. 1, the piston rod, 212, is connected by a link, 263, with an arm, 264, on a rock shaft, 259, provided with arms, 258, each of .which is connected by a' link,'257, to 'an arm, 256, for rotating forwardly a cam, 255, of one of the rear wheel ybrake mechanisms, which in this instance, is

shown as comprising brake drums, 252 and separable braking shoes 253, pivoted at 254, and provided -with the usual retracting springs, 261. It is to be understood, further, that the particular form of brake mechanism and its connections with the actuator form n0 part of our present invention, The piston rod, 212. is connected in a similar whichin this instance is the usual foot lever pivoted to the chassis and provided with a retracting spring, 251. This lever is connected to the longitudinally movable valve sleeve, 216-216a, and reversing valve mechanism by any usual or desired means. In the present instance we have shown the lever, 250, connected by al link rod, 262, with a rectangular frame comprising longitudinally movable slide rods, 271, engaging guid ing apertures, 272, in parts secured to the cylinder heads and projecting therefrom, said rods being connected at their forward ends by cross rod, 273, extending around the piston rod, 212, and being provided at their rear ends with a cross rod, 274, which extends through a slot, 275, in the piston rod 212, and engages suitable apertures in the sleeve, 216, so that the sleeve and valve mech- 4anism, including the collar valves,.227 and A229, may be shifted longitudinally with respect to thepiston. 210. by the operation of the foot lever, and in the reverse directio by the retracting spring, 251. i

Our'invention also contemplates, as before stated the employment of means whereby one of the pistons, as the auxiliary or fioating piston, 210a, may be permitted to remain stationary while the main piston is operated, thereby eiecting the operation of one set of brakes, only, and for releasing the said auxiliary or floating piston, to secure the simultaneous operation of the brake mechanisms connected with both pistons when required under the control of the operator. This is particularly advantageous in connection with an automobilevhaving four wheel brakes, as it enables theoperator to apply the brakes of two wheels. as the rear wheels, under ordinary working conditions, and also to bring into action the brakes of all four wheels in any emergency, or when it is desired to make a suddenstop, or when' additional braking power is required, as on very steep hills. TheV piston rod, 212, connected with the floating piston, is provided in this instance with'a groove or recess, 280, adapted to be engaged by a rounded spring detent, 281, mounted in a recess, 282, in the sleeve, 213A, of the actuator cylinder, 202. and provided with a spring, 283, held in position by a screw plug, 284. screwed into the recess, 282, by means of which the tension of the spring may be adjusted. The engage` ment of the detent. 281, with the recess, 280, in the piston rod, 212, is such that the auxiliary or floating piston, 210, will be normally held against movement when the valve mechanism of the actuator is moved into position to connect the central portion of the actuator cylinder with the suction, thus per,`

sol

mitting the main piston, 210 connected with the valve sleeve, to be actuated in either directionto apply and release the brakes connected therewith.

In the operation of the apparatus, when it is desired to apply only one set of brakes, the operator willlldepress the foot lever 250, thereby shifting the sleeve .216 and the reversing Valve mechanism in the direction of the arrow, Fig. 2, and moving the valves into the position shown in Fig. 3. -This releases the sealing valve 218 and permits it to be opened by the suction and brings the low pressure ports 224, into communication with the central'space A1 between the pistons and the high pressure ports 225 into com-A munication with chamber 230 communicatino with the opposite end portions of the cylinder, thus exhausting air from the central portion A1 and admitting air to the end portions of the cylinder. -As the piston rod 212ZL is held in locked position by the detent- 281, the'loating piston 210a will remain stationary and the piston 210 will move inwardly and apply the brakes connected therewith. It will be understood that if the pedal 250 is moved forward and held, the movement of the piston will follow until the piston 210 covers the low pressure ports, when it will be held in balanced condition, until a further movement of the valve mechanism under the actuation of the KYpedal takes place, a further forward movement of the pedal is instantly followed by a movement of the piston andthe brake mechanism can be applied with the same accuracy and delicacy as is obtained by the usual foot operated brake.

lVhen the operator releases the pedal 250, -it will be moved in the opposite direction by spring 251, thereby shifting the valve sleeve and reversing valve mechanism so as to place the low pressure munication with chamber 230, and the cylinder end portions and the high pressure ports, 225` in communication with central space A1 between the pistons, exhausting air from the end portions of the cylinder and admitting atmospheric air to central space A1,* and moving piston 210 back to normal position and releasing the brakes connected therewith. I

ln case more than normal braking is required, the piston' 210 is actuated until ar-- rested by the application of its connected brake mechanism as before described and a vfurther depression of the brake pedal suiticient to actua-te the valve sleeve, 2-16a`to its full extent will increase the suction within the ce-ntral space', A1, in the cylinder between the pistons. -When the suction has increased suiciently to enable the piston, 210L to overcome the retarding influence of the detent, the latter will yield and be forced down- .ward against its retracting spring, thus perports 224, in com'-` nceafeie mitting the floating piston, 210, to move inwardly and apply the brake mechanism connected therewith, as the front wheel brakes. -1 This movement of the floating piston, 210m',l

is retarded by the restricted size of the pas- Y sage, 270, prevent-ing the too sudden application of the brakes connected to piston, 2101, thereby diving the operator the opportuni-ty of slightly releasing the brakes, if he so desires, before the full effective -force of the additional two brakes is reached. rEllis passage may be provided with an adjustable valve, if desired, or the pipe, 270, may be of such size to provide the desired restricting effect. VVhe-n the reversing valve mechanism is shifted in the opposite direction by the brake pedal under the action of its retracting spring, both pistons will return to their normal positions, and as soon as the auxiliary or floating piston, 2101, is moved far enough to bring the groove or recess, 280, into engagement with the detent, 281, the

latter will spring into place and again lock the auxiliary piston. This construction will', therefore, enable the operator to actuate one of said pistons, and the brake'mechanism connected therewith, as the brakes for the rear, wheels or both pistons, and the brakes for all four wheels, as may be required.

It will also be noted that by reason of the lost motion between the piston, 210. and the reversing valve mechanism, that if the brake pedal, 250, isactuated and for any reason the pressure fails, further pressure on the pedal will bring the collar valves, 227, and 229, against the ends of the Ichambers, 228 and 230, automatically venting the cylinder, and the operator can then apply physical pressure to the brake pedal to directly move the piston, 210, -thus applying the brakes connected therewith by direct physical force of the operator, and thereby preventing/what otherwise might result in an accident. It'- is also to be noted that in the operation of our improved brake mechanism by means of the herein described power actuator, the operator operates the brake pedal in exactly .the same manner as to direction of movement and extent. of movement as is usual in installations where the power is applied wholly by the operator so that it isV unnecessary for the operator to learn a new mode of operation, while at 4comprising a cylinder closed at a communicating passage connecting its end portions, means for establishing diiierental pressures in the central portion of the cylinder between said pistons and the connected end portions, including reversing valve mechanism, an operator operated part, connections therefrom to the reversing valve mechanism, a piston rod connected with each of said pistons and extending through the end of the cylinder adjacent thereto, and locking mechanism for locking one of said piston `rods and its connected piston with respect to the cylinder to prevent movement t ereof, and independent brake mechanisms connected respectively to said piston rods.

2. The combination of a ower actuator comprising a cylinder close at both ends, a pair of double acting pistons located in the cylinder, said cylinder being provided with a communicating passage` connecting its en d portions, means for establishing differential pressures in the central portion of the cylinder between said pistons and the connected end portions, including reversing valve mechanism, an operator operated part, connections therefrom to the reversing valve mechanism, a piston rod connected with each of Said pistons and extending through the end of the cylinder adjacent thereto, independentbrake mechanism connected to each of said piston rods, one of said piston rods being provided with a spring actuated detent for `normally holding it and its connected piston from movement with respect to the cylinder. v

3. The combination of a power actuator both ends, a pair of double acting pistons located in the cylinder, said cylinder being provided with a communicating passage connecting its end ortions, means for establishing differentia pressuresin the central portion of the cylin er between said pistons and the connected end portions, including reversing valve mechanism, an operator operated part, connections therefrom to the reversing valve mechanism, a piston rod connected with each of said pistons and extending through the end of the cylinder adjacent thereto, independent brake mechanism connected to eachl of said piston rods, one of said piston rods being provided with a recess, and a spring actuated detent supported in a part connected with the cylinder and provided with a rounded portion engaging the 'recess in the 65 adjacent p iston rod, for normally holding it and its connected piston from movement with respect to the cylinder.

4. The combination of a power actuator comprisi-ng'a cylinder closed at both ends, 60 a pair of double acting pistons located in the cy inder, said cylinder` being provided with a communicating passage connecting its end portions, means for establishing differential pressures in the central portion of the cylinder between said pistons and the connected end portions, including reversing valve mechanism, an operator operated part, connections therefrom to the reversing valve mechanism, a piston rod connected with each of said pistons and extending through the end of the cylinder adjacent thereto, and locking mechanism for locking one of-said piston rodsand its connected piston with respect to the cylinder to prevent movement thereof, independent brake mechanisms connected respectively to said piston rods, said communicating passagebetween the end portions of the cylinder being constructed to restrict the passage of air therethrough to prevent the too sudden movement of the piston connected with` the .lock

engaging piston rod when the locking mechanism is released. 4

In' testimony whereof we affix our signa- 85 tures.

CALEB S. BRAGG. VICTOR W. KLIESRATH. 

